1. Field of the Invention
This invention relates to a security system, and, in particular, it relates to a security system which is a system for home security that is provided with communication functions of detecting illegal intruders from outside and reporting this information to those to whom it is necessary.
2. Description of the Related Art
Many conventional home security systems are systems for detecting whether or not there is an intruder by means of various sensors, which are installed in places for preventing crime. Most of such sensors utilize infrared radiation, and if something unusual happens, it is reported. For example, when an illegal intruder appears, the sensors detect it and send unusual signals to a centralized monitoring center using public telephone lines (including cell-phone systems) or dedicated lines. The monitoring person in the centralized monitoring center, who has confirmed something unusual has happened, send security guards to the place.
However, the greatest problem in this system is that we can not have sufficient confidence about an intruder solely from the sensor signals. If only sensors such as infrared sensors are used, error signals might be generated in many cases, and also in such a case, a reporting signal, which is the same type as when an intruder appears, is sent to the centralized monitoring center. The centralized monitoring center will take same measures as when there is an intruder. Therefore, these measures are in vain in such instances.
One of the monitoring methods for precisely confirm the presence of an intruder is to add image information, which is being tried. Such an example is described in Japanese Patent Application Publication No. 11-224,383 A, which was published in 1999. This system has a function of displaying the information from cameras, which are installed in places to be monitored, on the user terminal using a PHS system. This system also entails problems to be improved.
The first problem is that, although reporting information is transmitted promptly by means of this system, it also contains undesired or redundant information that are added to the requested information. As a result, excessive time is required for the user to have a confidence as to the presence of an intruder. For this reason, users who need information rapidly find above one is inconvenient and the communication costs for transmission of information is comparatively high. The second problem is that it was difficult to control multiple cameras, which are installed in sites to be monitored. According to the patent publication described above, just one monitoring camera is shown, which is installed in the site to be monitored. Conventionally, there was no system that could make reports where multiple monitoring cameras were used. The third problem relates to a function of saving image data. By means of the technology disclosed in the patent publication described above, the camera images are stored in memory as video images accompanied by a time delay. In this case, it is difficult to promptly pick up required video images and there are limits to memory capacity. Further, as described in above patent publication, installing an image recording device in the place to be monitored is not necessarily for preventing advantage.
Accordingly, in the light of the problems described above, the object of this invention is to provide a security system by which efficient transmission and practical use of accurate information can be realized in a relatively simple structure and with a low cost.